HOW TO MAKE A SMARTPHONE-POWERED HOLOGRAM

Holograms aren’t just for droids and dead rappers. You can make your own with a piece of transparency paper and a four-sided hologram video. Properly folded, the transparency will combine the images on a phone or tablet screen to create “a reflection that gives you the illusion of an object hovering in space,” says Alex Cronin, a physicist at the University of Arizona.